pactn.契约；协定；条约pactum illicitum[法] 非法协定, 非法协约pacterial enzyme细菌酶Pactice teaching实践教学pactional damages约定损害赔偿金pact test specimen却贝冲击试样pact specimen retest冲击试样复试pactum de contrahendo[法] 缔约承诺pactum de retrovendendo回购权协议pactical teaching model实践教学模式Pactum de retro vendendo典卖简约回卖